Elsevier

Nuclear Physics

Volume 22, Issue 3, February 1961, Pages 451-467
Nuclear Physics

The polarization of neutrons from the Li7(p, n)Be7 reaction (II)

https://doi.org/10.1016/0029-5582(61)90395-9Get rights and content

Abstract

The polarization of the Li7(p, n)Be7 neutrons has been deduced from measurements of the left-right asymmetry in the scattering of these neutrons from a liquid oxygen analyzer. Angular distributions of the polarization (Pn) were measured at 2.2, 2.6 and 3.0 MeV covering angular ranges (laboratory system) of from 30° to 70°, 30° to 115° and 30° to 70°, respectively. For neutrons emitted at 50°, additional measurements were made at proton energies between 2.1 and 3.1 MeV. At 2.6 MeV Pn is close to zero at 105° and 115°, suggesting that at least two states formed by the same initial channel spin and having l1+l2 ≧ 2 contribute to the reaction. The polarization at 50° as a function of energy decreases rapidly from about 0.5 at 2.15 MeV to a broad minimum centered at 2.45 MeV where the polarization is about 0.2 and then increases to a constant value near 0.3 at bombarding energies above 2.7 MeV. Polarizations and differential cross sections calculated assuming that the reaction is described by the levels in Be8 which were postulated by Macklin and Gibbons to account for their measured total cross sections are not consistent with the experimental data. The results of calculations based on several other sets of level parameters are discussed. The unequal values of the reduced widths for emission of protons and neutrons observed for at least one level in Be8 are explained in terms of the mixing by electromagnetic effects of states in Be8 with the same spin and parity, but different isobaric spin.

References (34)

  • W. Haeberli (private...
  • L.A. RadicatiL.A. Radicati
  • S.E. Darden et al.

    Nuclear Physics

    (1960)
  • R.L. Macklin et al.

    Phys. Rev.

    (1958)
    J.H. Gibbons et al.

    Phys. Rev.

    (1959)
  • H.W. Newson et al.

    Phys. Rev.

    (1957)
  • R.K. Adair

    Phys. Rev.

    (1954)
    R.K. Adair

    Phys. Rev.

    (1952)
  • H.R. Striebel et al.

    Nuclear Physics

    (1958)
  • R. Taschek et al.

    Phys. Rev.

    (1948)
  • A. Okazaki

    Phys. Rev.

    (1955)
  • R.K. Adair

    Phys. Rev.

    (1953)
  • R.G. Thomas

    Phys. Rev.

    (1951)
  • J.M. Blatt et al.

    Revs. Mod. Phys.

    (1952)
  • A. Simon et al.

    Phys. Rev.

    (1953)
  • D.R. Inglis

    Phys. Rev.

    (1948)
  • N.P. Heydenburg et al.

    Phys. Rev.

    (1948)
    N.P. Heydenburg et al.

    Phys. Rev.

    (1948)
  • P.R. Malmberg

    Phys. Rev.

    (1956)
  • A.M. Lane et al.

    Revs. Mod. Phys.

    (1958)
  • Cited by (5)

    • New broad Be8 nuclear resonances

      2005, Physical Review C - Nuclear Physics

    Work supported in part by the U.S. Atomic Energy Commission and by the Graduate School from funds supplied by the Wisconsin Alumni Research Foundation.

    Now at the Clarendon Laboratory, Oxford University, Oxford, England.

    ††

    On leave from the University of Notre Dame, Indiana. Some of the calculations described in this paper were performed while the author was at the University of Notre Dame and were supported in part by the joint program of the Office of Naval Research and the U.S. Atomic Energy Commission.

    On leave from Atomic Energy of Canada, Limited, Chalk River, Ontario.

    ‡‡

    On leave from the Institute for Nuclear Research of the Polish Academy of Science, Warsaw, Poland.

    View full text